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What is Wind? Wind is a by-product of solar energy, caused by uneven heating
and cooling of the earth’s surface. Low-pressure zones are created where the
warmer air rises and pulls in cooler air. Geographical features such as hills,
valleys, trees, buildings and lakes directly affect velocity and Wind flow.
Seasonal weather patterns and the spin of the planet are also issues that
directly affect wind velocity and wind flow. A wind turbine is needed to convert wind energy into an energy (electricity) that we can use. The blades of a wind turbine catch the wind and cause the rotor to turn. As a result, this turning drives a generator that converts the wind energy into electricity. Generally speaking, wind energy should be consumed as it is produced; however it is possible to store excess energy using batteries. Darrieus VS Savonius VS Horizontal Darrieus,
Propeller type and Savonius are three different implementations of wind
turbines. The Propeller type wind turbine is what is considered a Horizontal
Axis Wind Turbine (HAWT) where the propeller rotates about a horizontal axis.
The Darrieus and Savonius designs are a Vertical Axis Wind Turbine (VAWT) where
they rotate about a vertical axis.
The shape of the Darrieus is comparable to that of an egg beater, it requires a lift force in order for it to rotate and during rotation, creates an imagery of an egg beater. This type of design does not require the turbine to be turned to face the wind because it can accept wind from all different directions because of the design. The main mechanical features of this turbine such as the powertrain, generator and controls are located near ground level and make it easier to maintain. The Darrieus design causes less electromagnetic interference than the conventional propeller type design. The Darrieus requires an induction motor because it is normally not self starting, the induction motor is used for the initial few revolutions to get the Darrieus to start moving. There is also a rather high tendency for failures and accidents in which the speed of rotations could not be controlled and hence leading to the collapse of the entire structure. Propeller (HAWT - Lift Force):
The propeller type turbine is similar in appearance to a propeller on an airplane. It requires a lift force in order for it to rotate about a horizontal axis. A utility size propeller type turbine requires constant monitoring of the velocity of wind and direction of wind in order to fully utilize the full force of the wind. The utility sized propeller type requires a motorized mechanism with which will rotate the turbine into the direction of the wind and exploit the full potential provided by the current wind situation. For small wind turbines, a Tail Vane is needed to do the job. The most common material of which the propeller comprises of is fiberglass, one definite shortcoming of fiberglass is that it cannot withstand the stress of rotating at very high speed when the velocity of the wind is high enough. Brakes are also required to avoid overloading of the generator as its operating range cannot be exceeded. As compared with the vertical designs, this horizontal device has most of its mechanisms up by the propeller and depending on the size of tower used, it can be a big task to service these machines. The propeller is required to be raised off the ground about 150-300 feet for the big ones and 50-120 feet for the small ones which is a lot more than is required for a vertical axis turbine, this is in order to avoid turbulent winds generated by other structures closer to the ground, turbulence can severely damage a propeller and mechanisms connected to it which would be very expensive to replace. This type of wind generator should be mounted at least 20 feet higher than any nearby obstructions (300 feet away) to avoid turbulent conditions. Typical Customers for small wind turbines have at least 1 acre of property. An estimated 65% of the US has sufficient wind resources to sustain a Small Wind Turbine. The suggested requirement of wind to sustain a Small Wind Turbine is Class 3 winds and higher. Savonius (VAWT - Drag Force):
The Savonius type of turbine is the type that
Zephyr has based its design around. The Savonius type requires a drag force in
order for it to rotate about its vertical axis. Savonius type turbines are
resistant to Turbulence and can be mounted closer to the ground, they also do
not require shifting or rotating of the turbine in order to utilize the full
potential of the wind. The Savonius type turbine has an efficiency nearly as
good as the propeller type and Darrieus type turbines, the efficiency like all
other designs are dependent upon how well engineered the turbine is. The
Savonius type also causes less electromagnetic interference when compared with
the propeller type turbines. Net metering is a method for customers with renewable energy generating facilities to sell their electricity back to the utility company. Net Metering meters the production and usage of energy at the facility. Electricity usage metered will be offset by the electricity produced with their wind turbine, it will spin the existing utility meter backwards which will in turn provide the consumer with retail value of the electricity produced by their wind turbine, this is performed until the bill is zeroed. In numerous states, if the electricity produced by the customer is more than their usage during the billing period, the excess energy is credited back to the user at the wholesale rate, this credit can be used during future billing periods. In the United States, net metering is now federally legislated but each of states may have varied policies regarding net metering. Importance of Net Metering: · When electricity is generated by a renewable generation facility, the electricity generated is an intermittent resource and can’t always be used when it is generating.· There is a reduced installation cost as a single meter is all that is required for the usage of net metering. · Simple system encourages the use of small scale wind and solar energy systems. · Credited at retail rate helps financial payback. Environmental Hazard Issues: Environmental hazard issues associated with traditional methods of generating electricity (such as using Fossil fuel and Nuclear power plants) can exert a range of impact on air, water and land.Climate Change: Problems arise such as global climate changes. Burning of fossil fuels (such as coal, oil and natural gas) releases carbon in the fossil fuels and is then transformed into CO2 which is the predominant gas contributing to greenhouse effects. Greenhouse effect allows energy from the sun to pass thru the Earth’s atmosphere and traps it in the form of heat. It raises the average global temperatures at an accelerated pace which can causes concerns such as:· Human health: increased infectious disease caused by nurturing the spread of disease carrying mosquitoes and rodents. · Extreme weather impacts: increased frequency of severe heat waves. · Coastal Zone and Small island flooding: once global temperature raises, sea level will rise. This will cause rising sea levels and severe ocean storms. · Forest Devastation: since trees and vegetation are slow to respond to climate cycles, they may be unable to survive due to unpredictable weather. · Agriculture: changing weather patterns associated with changing global climate patterns pose major threats for farmers. Acid Rain: Acid rain is a term used to describe rain, mist or snow that is more acidic than usual. Normal rainwater has a pH of approximately 5.6 whereas acid rain has a pH of about 4.4. Burning fossil fuels emits two different ingredients such as SO2 and NOx, when these ingredients are combined with moisture these pollutants return to the earth as acids. Acid rain is accountable for the disappearance of several marine species, mortality and slow growth of a several tree species, corrosion of metals and deterioration of paint/stone and reduced visibility due to SO2/NOx emissions.Ozone: The Ozone layer provides a layer of protection from the ultraviolet rays of the sun. The burning of fossil fuels emits NOx and when combined with volatile organic compounds, creates ozone pollution and that in turn creates urban smog (a form of Ground Level Ozone). Ground level ozone can cause respiratory problems, allergic reactions and visual problems in humans. It also interferes with plants' ability to turn sunlight into usable energy.Pollution of Water: Due to routine operations and power plant machinery maintenance, certain procedures will pollute bodies of water. Different procedures are used to clean and cool the machinery, these procedures emit impurities into the water that washes them and is then washed into the sewage system. Pollutants such as copper, iron, nickel and cleansing chemicals are mixed into the water during routine operations/maintenance, these contaminants are hard to remove from water and are devastating to the environment.Power plant premises and surrounding area Land Impacts: On Premise: The life expectancy of a nuclear power plant is about 40 years. During the life of a nuclear power plant, electricity generators tend to leave their land scarred and polluted due to the waste produced by the usage and maintenance of the generators. There will be a major reduction in the value of land during the years of operation of the power plant. Due to the land being contaminated by toxic residues and pollutants during the operation of the power plant, even after the power plant has been put out of commission, the piece of land which once occupied by the power plant and surrounding area can no longer be used as a site for future development due to hazardous living conditions.Surrounding area: Most electricity generation facilities also generate waste by-products which is a toxic substance, the waste is usually sent off to a landfill at a remote location and therefore the pollutants reach a far greater distance than just the premises of the power plant. The waste if not stored properly may leak and reach underground water sources which will contaminate the once pure water source. The mining of coal erodes hills and mountains, leaving a visually unattractive sight to visitors of the area. Natural gas piping across landscapes disrupts wildlife habitat, violates private land premises and eliminates the use of the land for other uses.Benefits of using small wind turbine: How much savings per bill?Depending on the installation, most owners expect anywhere from 50%-90% savings per electric bill. How long does it take to pay off cost of wind turbine in the United States? It takes approximately 6 to 15 years to pay off the cost of the wind turbine, the variance is dependent mostly on the location of the installation. Variations in the incentives and cost of electricity due to different state regulations lead to a difference in the length it takes to pay off the cost of a wind turbine. How much of an impact does a wind turbine help in terms of the environment? 1.2 tons of air pollutants and 200 tons of greenhouse gases will be generated by burning fossil fuels during the lifetime of a wind turbine. A small wind turbine produces no pollution at all, hence it is a zero emission generator. What government incentives are there to owning a small wind turbine? For US residents, there are incentives given by the government dependent on the area where you reside. Refer to the link to find your location: Database of State Incentives for Renewable Energy
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Copyright © 2008
Zephyr Alternative Power Inc.
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